("For the reconnaissance service are not more troops to be used than the purpose requires.

The reconnaissance troops shall be timely concentrated on the most important direction, especially if superior enemy reconnaissance forces are to be expected. Only the minimum (most necessary) shall be allocated for secondary directions.

It is to strive that the reconnaissance according to the situation be densified with held back reconnaissance forces at any time, expanded (enlarged, extended) or, if necessary, also to be sent into a new direction.")

This paragraph of the classic Truppenführung field manual (pre-WW2Wehrmacht) reminded me of an interesting detail; Wehrmacht reconnaissance theory/doctrine was offensive (= optimistic), just as most reconnaissance doctrines seem to be.

The pre-WW2 division of the German army generals into defensive, offensive and armour schools of thought had experienced a shift towards offensive during the 30's and towards armour after the fall of France. The defensive school had mostly assumed that front lines would quite reliably prevent penetrations and did not prepare reconnaissance guidance for the finding and tracking of fast enemy forces that had penetrated the front line (at least not behind the HKL, main line of resistance).

Other defensive skills were neglected as well till they had to be re-learned during the winter of 41/42. Delaying tactics, breaking contact and withdrawals were apparently not trained well-enough.

Back to defensive reconnaissance; Soviet tank units often penetrated the thin front line (often rather lines of pickets and hedgehog self-defence positions) quite often and they were very often particularly vulnerable because their escorting infantry (desants) experienced high losses during breakthrough fights.

The tanks were still able to wreak havoc among German rear units and had to be found, tracked, hunted and destroyed (preferably in ambushes).

That's where a huge problem intervened; there were no forces for the find & track part. Luck (radio reports from surviving rear units, for example) and improvisation had to suffice.

Late war tank destroyer, heavy tank and assault gun units organisations often had a cheap solution for this problem:

They swarmed out, reported their findings and the anti-tank forces could move into advantageous positions for the AT fight.

I have yet to see an equivalent in modern field manuals; reconnaissance against enemy stragglers and incursions on supposedly friendly terrain doesn't seem to get much attention nowadays.

There are certain area recce, zone recce doctrines (rather patterns) in field manuals, but the idea that this could be used for purposes like the described one seems to be absent.

Unsurprisingly, much of the modern Western literature seems to assume that we'd be on the operational offensive in a military vs. military war. That's quite ahistorical (save for extremely one-sided conflicts such as OIF); a look at the culminating point of attack concept should suffice to remember us that periods of high activity (offence, defence) and relatively low activity (static defence) tend to alternate.